Methods of heavy reformate conversion into aromatic compounds

ABSTRACT

Method of making BTX compounds including benzene, toluene, and xylene, including feeding heavy reformate to a reactor containing a composite zeolite catalyst. The composite zeolite catalyst includes a mixture of layered mordenite (MOR-L) comprising a layered or rod-type morphology with a layer thickness less than 30 nm and ZSM-5. The MOR-L, the ZSM-5, or both include one or more impregnated metals. The method further includes producing the BTX compounds by simultaneously performing transalkylation and dealkylation of the heavy reformate in the reactor. The composite zeolite catalyst is able to simultaneously catalyze both the transalkylation and dealkylation reactions.

CROSS REFERENCE To RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 16/299,723 filed Mar. 12, 2019 and claims priority to EuropeanApplication No. 18382168.5, filed Mar. 14, 2018, which are herebyincorporated by reference in their entirety.

TECHNICAL FIELD

Embodiments of the present specification generally relate to methods ofmaking aromatic compounds, and specifically relate to methods of makingbenzene, toluene, and xylenes from a heavy reformate feed and a catalystfor utilization in the same.

BACKGROUND

Heavy reformate (HR), containing mainly C₉₊ aromatics, is the fractionthat remains after extraction of the more valuable BTX (benzene,toluene, xylene) fraction from the catalytic reformate or the pyrolysisgasoline. Traditionally this fraction was directly added to the gasolinepool. However, due to the restriction of the benzene content in gasolineby environmental regulations, it is important to find alternative waysof upgrading this stream into other valuable products. One option is toconvert the heavy aromatics in the heavy reformate into additional BTXcompounds. Heavy reformate may be converted into xylenes, benzene, andtoluene by dealkylation of the C₉+ alkylaromatics to produce toluene,and further transalkylation of the toluene formed by dealkylation withother C₉₊ alkylaromatics present in the feed to produce benzene andxylenes. Regardless, these means to produce BTX compounds bysimultaneous dealkylation and transalkylation have limited efficiency,because of the sequential nature of the conversion reaction processwhere products of a first reaction are utilized in a second reaction.

SUMMARY

Accordingly, ongoing needs exist for catalysts suitable for efficientlyconverting heavy reformates to produce benzene, toluene, and xylenes.Embodiments of the present disclosure are related to composite zeolitecatalyst formulations and methods of making benzene, toluene, andxylenes using the composite zeolite catalyst. The composite zeolitecatalysts may convert a mixture of heavy aromatic compounds (such asthose present in heavy reformate), particularly C₉₊ aromatichydrocarbons to benzene, toluene, and xylenes, and particularly tocommercially valuable xylenes.

According to one embodiment, a method of making BTX compounds includingbenzene, toluene, and xylene is provided. The method includes feedingheavy reformate to a reactor. The reactor contains a composite zeolitecatalyst including a mixture of layered mordenite (MOR-L) having alayered or rod-type morphology with a layer thickness less than 30nanometers (nm) and ZSM-5. The MOR-L, the ZSM-5, or both include one ormore impregnated metals. The method further includes producing the BTXcompounds by simultaneously performing transalkylation and dealkylationof the heavy reformate in the reactor. The composite zeolite catalyst isable to simultaneously catalyze both the transalkylation anddealkylation reactions.

According to another embodiment, a composite zeolite catalyst isprovided. The composite zeolite catalyst includes a mixture of layeredmordenite (MOR-L) having a layered or rod-type morphology with a layerthickness less than 30 nm and ZSM-5. The MOR-L, the ZSM-5, or bothcomprise one or more impregnated metals.

Additional features and advantages of the described embodiments will beset forth in the detailed description which follows, and in part will bereadily apparent to those skilled in the art from that description orrecognized by practicing the described embodiments, including thedetailed description which follows, the claims, as well as the appendeddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an X-Ray Diffraction (XRD) pattern of commercially availableMordenite and Layered Mordenite (MOR-L).

FIG. 2 is a TEM micrograph micrograph of MOR-L synthesized in accordancewith one or more embodiments of the present disclosure.

FIG. 3 is a TEM micrograph of a commercially available Mordenite(CBV21A).

FIG. 4 is a ²⁷Al-NMR spectra for MOR-L and a commercially availableMordenite.

FIG. 5 is a Fourier Transform infrared (FT-IR) spectra of commerciallyavailable Mordenite and MOR-L.

FIG. 6 is a graph of Methylethylbenzene (MEB) conversion of a simulatedheavy reformate stream obtained with commercially available zeolitecatalysts, MOR-L impregnated with 0.3 weight percent (wt. %) rhenium,and a composite zeolite catalyst in accordance with one or moreembodiments of the present disclosure.

FIG. 7 is a graph of Trimethylbenzene (TMB) conversion of a simulatedheavy reformate stream obtained with commercially available zeolitecatalysts, MOR-L impregnated with 0.3 wt. % rhenium, and a compositezeolite catalyst in accordance with one or more embodiments of thepresent disclosure.

FIG. 8 is a graph of overall conversion (MEB+TMB) of a simulated heavyreformate stream obtained with commercially available zeolite catalysts,MOR-L impregnated with 0.3 wt. % rhenium, and a composite zeolitecatalyst in accordance with one or more embodiments of the presentdisclosure.

FIG. 9 is a graph of xylenes yield from a simulated heavy reformatestream obtained with commercially available zeolite catalysts, MOR-Limpregnated with 0.3 wt. % rhenium, and a composite zeolite catalyst inaccordance with one or more embodiments of the present disclosure.

FIG. 10 is a graph of A₁₀ yield (yield of aromatics with 10 carbons)from a simulated heavy reformate stream obtained with commerciallyavailable zeolite catalysts, MOR-L impregnated with 0.3 wt. % rhenium,and a composite zeolite catalyst in accordance with one or moreembodiments of the present disclosure.

FIG. 11 is a graph of A₁₀₊ yield (yield of aromatics with more than 10carbons) from a simulated heavy reformate stream obtained withcommercially available zeolite catalysts, MOR-L impregnated with 0.3 wt.% rhenium, and a composite zeolite catalyst in accordance with one ormore embodiments of the present disclosure.

FIG. 12 is a graph of light hydrocarbon yield from a simulated heavyreformate stream obtained with commercially available zeolite catalysts,MOR-L impregnated with 0.3 wt. % rhenium, and a composite zeolitecatalyst in accordance with one or more embodiments of the presentdisclosure.

FIG. 13 is a graph of toluene yield from a simulated heavy reformatestream obtained with commercially available zeolite catalysts, MOR-Limpregnated with 0.3 wt. % rhenium, and a composite zeolite catalyst inaccordance with one or more embodiments of the present disclosure.

FIG. 14 is a graph of ethylbenzene yield from a simulated heavyreformate stream obtained with commercially available zeolite catalysts,MOR-L impregnated with 0.3 wt. % rhenium, and a composite zeolitecatalyst in accordance with one or more embodiments of the presentdisclosure.

FIG. 15 is a graph of benzene yield from a simulated heavy reformatestream obtained with commercially available zeolite catalysts, MOR-Limpregnated with 0.3 wt. % rhenium, and a composite zeolite catalyst inaccordance with one or more embodiments of the present disclosure.

FIG. 16 is a graph of TMB conversion of an industrial heavy reformatestream obtained with commercially available zeolite catalysts, MOR-Limpregnated with 0.3 wt. % rhenium, and a composite zeolite catalyst inaccordance with one or more embodiments of the present disclosure.

FIG. 17 is a graph of MEB conversion of an industrial heavy reformatestream obtained with commercially available zeolite catalysts, MOR-Limpregnated with 0.3 wt. % rhenium, and a composite zeolite catalyst inaccordance with one or more embodiments of the present disclosure.

FIG. 18 is a graph of overall conversion of an industrial heavyreformate stream obtained with commercially available zeolite catalysts,MOR-L impregnated with 0.3 wt. % rhenium, and a composite zeolitecatalyst in accordance with one or more embodiments of the presentdisclosure.

FIG. 19 is a graph of xylenes yield from an industrial heavy reformatestream obtained with commercially available zeolite catalysts, MOR-Limpregnated with 0.3 wt. % rhenium, and a composite zeolite catalyst inaccordance with one or more embodiments of the present disclosure.

FIG. 20 is a graph of A₁₀ yield from an industrial heavy reformatestream obtained with commercially available zeolite catalysts, MOR-Limpregnated with 0.3 wt. % rhenium, and a composite zeolite catalyst inaccordance with one or more embodiments of the present disclosure.

FIG. 21 is a graph of A₁₀₊ yield from an industrial heavy reformatestream obtained with commercially available zeolite catalysts, MOR-Limpregnated with 0.3 wt. % rhenium, and a composite zeolite catalyst inaccordance with one or more embodiments of the present disclosure.

FIG. 22 is a graph of light hydrocarbon yield from an industrial heavyreformate stream obtained with commercially available zeolite catalysts,MOR-L impregnated with 0.3 wt. % rhenium, and a composite zeolitecatalyst in accordance with one or more embodiments of the presentdisclosure.

FIG. 23 is a graph of toluene yield from of an industrial heavyreformate stream obtained with commercially available zeolite catalysts,MOR-L impregnated with 0.3 wt. % rhenium, and a composite zeolitecatalyst in accordance with one or more embodiments of the presentdisclosure.

FIG. 24 is a graph of ethylbenzene yield from an industrial heavyreformate stream obtained with commercially available zeolite catalysts,MOR-L impregnated with 0.3 wt. % rhenium, and a composite zeolitecatalyst in accordance with one or more embodiments of the presentdisclosure.

FIG. 25 is a graph of benzene yield from an industrial heavy reformatestream obtained with commercially available zeolite catalysts, MOR-Limpregnated with 0.3 wt. % rhenium, and a composite zeolite catalyst inaccordance with one or more embodiments of the present disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of a method ofmaking benzene, toluene, and xylene by conversion of heavy reformatewith a composite zeolite catalyst.

The main components of heavy reformate are ethyl-toluenes(methyl-ethyl-benzenes, MEB) and trimethyl-benzenes (TMB). Thestructures of the MEB isomers and TMB isomers are provided infra.

These aromatics can be converted into the more valuable BTX compounds bymeans of dealkylation of the C₉₊ alkylaromatics, or by transalkylationof these compounds with benzene or toluene. The aim of the process is tomaximize the production of xylenes by de-ethylation of MEB andtransalkylation of TMB. Specifically, transalkylation of TMB present inthe feed with the toluene formed as a product of de-ethylation of MEB.

The dealkylation of MEB to toluene and ethane is provided infra.Dealkylation of MEB in the presence of a Brønsted acid catalystinitially produces toluene and ethylene. However, the ethylene may besubsequently hydrogenated to ethane in the presence of an adequatehydrogenation catalyst. If the hydrogenation functionality is noteffective, portions of the ethylene may not be hydrogenated to ethaneand as such may be present in the product gases, or it may be convertedto oligomers or other products.

The transalkylation of TMB present in the heavy reformate with thetoluene formed from dealkylation of MEB to toluene and ethane isprovided infra.

Additionally, toluene and TMB may also undergo a disproportionationreaction leading to xylenes and benzene or xylenes andtetramethylbenzenes (A₁₀ ), respectively. The chemical reactions areprovided infra.

A composite zeolite catalyst may be formed from a mixture of layeredmordenite (MOR-L) and ZSM-5 zeolite catalysts. The composite zeolitecatalyst allows conversion of heavy reformate, or other aromaticreactant streams, in a single reactor. Specifically, the dealkylation ofMEB and the transalkylation of the produced toluene with TMB may beperformed in a single reactor, because of the proximity between thecrystals of MOR-L and ZSM-5 when physically mixed in a single reactor.The MEB dealkylation reaction is necessary in order to obtain thetoluene that has to react with the TMB in the feed for producing thedesired xylenes and benzene. Thus, the proximity of the ZSM-5 and MOR-Lcrystals obtained by the physical mixing of the MOR-L and ZSM-5 andreaction in a single reactor enables an improved and faster coupling ofboth consecutive reactions to produce benzene, toluene, and xylenes.

The composite zeolite catalyst in one or more embodiments comprisesMOR-L and ZSM-5. ZSM-5 is an aluminosilicate zeolite of the pentasilfamily of zeolites. ZSM-5 (Zeolite Socony Mobil-5) has a MordeniteFramework Inverted (MFI) framework with an ordered crystal structurepresenting intersecting 10-ring channels (5.1×5.5 and 5.3×5.6 angstrom(Å)). Mordenite (MOR), an aluminosilicate, comprises a molecularstructure of a framework containing chains of five-membered rings oflinked silicate and aluminate tetrahedra (four oxygen atoms arranged atthe points of a triangular pyramid about a central silicon or aluminumatom), with a crystalline structure presenting mono-directional channelsdefined by twelve-membered rings (6.5×7.0 Å). A commercially availableMOR is CBV21A from Zeolyst International (Conshohocken, Pa., USA).

Layered mordenite (MOR-L) and MOR comprise the same characteristicstructure, but differing morphology. With reference to FIG. 1, the X-raydiffraction (XRD) pattern for MOR-L and MOR (CBV21A) comprise the samepeaks demonstrating the same characteristic underlying the crystallinestructure. With regards to the differing morphology, MOR-L comprises alayered or rod-type morphology, and MOR comprises larger crystals. FIG.2 illustrates (TEM) images of the MOR-L crystal morphology, and clearlyshows the layered shape with limited growth in one of thecrystallographic directions. Similarly, FIG. 3 illustrates a TEM imageof the MOR crystal morphology for the commercially available CBV21A. Thecrystals of MOR are heterogeneous in size and irregular in shape andlarger than those of MOR-L. Additionally, the MOR crystals present nopreferential growth in any of the three space directions.

The MOR-L comprises a layered or rod-type morphology. In one or moreembodiments, the layer thickness of the layers or rods is less than 30nanometers (nm). The thickness is considered the smallest dimension ofthe MOR-L crystal. In further embodiments, the layer thickness of thelayers or rods is less than 28 nm, less than 25 nm, less than 22 nm,less than 20 nm, or less than 18 nm. The minimal layer thicknessproduces a MOR-L crystal with a greater external to internal surfacearea ratio than commercially available MOR as the MOR-L presents assheets or long and slender rods.

The method of making BTX compounds includes feeding heavy reformate to areactor, which contains the composite zeolite catalyst formed from amixture of MOR-L and ZSM-5. The BTX compounds are then produced bysimultaneously performing transalkylation and dealkylation of the heavyreformate in the reactor. The composite zeolite catalyst is able tosimultaneously catalyze both the transalkylation and dealkylationreaction with the combination of MOR-L and ZSM-5.

The composite zeolite catalyst including both MOR-L and ZSM-5 produces asynergistic effect and is capable of converting a heavy reformate feed,generally comprising at least 15 weight percent (wt. %) MEB and at least50 wt. % TMB, to BTX compounds within a single reactor. The presence ofZSM-5 component increases the amount of toluene in the reaction media asa result of the additional dealkylation activity originating from theZSM-5 component. The increased availability of toluene in the reactionmedia allows for increased reaction with the TMB present in the heavyreformate feed in conjunction with the MOR-L to yield BTX products,especially desirable xylenes. Additionally, as the TMB has more tolueneavailable for reaction, transalkylation of the A₉₊ aromatics from theheavy reformate feed is reduced, which also reduces the generation ofundesirable A₁₀₊ by-products.

Alkylaromatics, such as those present in a heavy reformate (MEB, TMB),in the presence of an acid catalyst, may undergo undesired reactions,which lead to formation of aromatics with 10 carbon atoms (A₁₀) or morethan 10 carbon atoms (A₁₀₊). If these A₁₀ and A₁₀₊ compounds cannotdiffuse out of the zeolite crystals through the pores of the crystallinestructure because of steric limitations, they may block part of thechannel systems or lead to bulkier coke precursors. The improvedconversion efficiency of the composite zeolite catalysts alleviates theformation of heavy alkylaromatics comprising A₁₀ and A₁₀₊ aromatics.Specifically, the proximity of the ZSM-5 and MOR-L as a mixture within asingle reactor allows the TMB of the feed to react preferentially withthe toluene formed by dealkylation of MEB on the ZSM-5 crystals, insteadof reacting with other TMB by transalkylation to form tetramethylbenzeneor heavier compounds. The reaction of the heavy reformate feed in asingle reaction in the presence of the composite zeolite catalyst,including ZSM-5 and MOR-L, results in higher selectivity to xylenes andreduced formation of A₁₀₊ and coke precursors, leading therefore toimproved catalyst life.

The reaction of the heavy reformate feed in a single reactor with thecomposite zeolite catalyst comprising ZSM-5 and MOR-L achieves improvedperformance in conversion of the heavy reformate to BTX compounds. Thisimprovement is even more profound when carrying out the transalkylationof a heavy reformate in the absence of added toluene or benzene, becausethese two aromatics must be produced in-situ from C₉₊ aromatics such aswith dealkylation of MEB contained within the feed. The proximatelocations of the MOR-L and ZSM-5 in the composite zeolite catalystthrough a physical mixture and reaction in a single reactor allows thetoluene produced from dealkylation of MEB to be more readily availablefor use in the transalkylation reaction of TMB or disproportionationreaction of toluene for the ultimate production of xylenes.

The MOR-L and ZSM-5 zeolite catalysts may be physically mixed in variousratios to produce a composite zeolite catalyst with varying degrees ofMEB and TMB conversion. In one or more embodiments, the MOR-L and ZSM-5are combined in a 50:50 to 90:10 weight ratio to form the compositezeolite catalyst. In various further embodiments, the MOR-L and ZSM-5are combined in a 50:50 to 80:20 weight ratio, 50:50 to 70:30 weightratio, 55:45 to 65:35 weight ratio, or an approximately 60:40 weightratio to form the composite zeolite catalyst. As previously indicated,an increase in ZSM-5 in the composite zeolite catalyst results in anincrease in the amount of toluene in the reaction media as a result ofthe additional dealkylation activity originated from the ZSM-5component. However, it will be appreciated that an increase in ZSM-5weight percentage (wt. %) requires a congruent reduction in MOR-L wt. %.An increase in ZSM-5 wt. % and reduction in MOR-L wt. % results in lesstransalkylation and an excess of toluene.

Moreover, the zeolite composite catalyst may be impregnated with metalsfor catalysis, for example, metals such as molybdenum, chromium,platinum, nickel, tungsten, palladium, ruthenium, gold, rhenium,rhodium, or combinations thereof. In one embodiment, the impregnatedmetal is rhenium (Re). The metal component may exist within the finalzeolite composite catalyst as a compound, such as an active metal oxide,an active metal sulfide or active metal halide, in chemical combinationwith one or more of the other ingredients of the composite, or as anelemental metal. The impregnated metal component may be present in thefinal composite zeolite catalyst in any amount that is catalyticallyeffective, for example from 0.01 to 20.0 wt. %, or from 2 to 5 wt. %, orfrom 0.1 to 1.5 wt. %, or approximately 0.3 wt. % of the compositezeolite catalyst particle.

Metals are added to the catalyst for their hydrogenation functionality.The dealkylation, transalkylation and disproportionation reactions takeplace on the Brønsted acid sites of the composite zeolite catalysts.However, the hydrogenation function of the metal component is utilizedto convert ethylene into ethane and may also enhance the desorption ofcoke precursors. The conversion of ethylene into ethane avoids theoligomerization of the olefin to products that may deactivate thecatalyst.

In one or more embodiments, the metals are incorporated into thecatalyst by ion exchange or impregnation of their salts in aqueoussolution. The catalysts with the incorporated metals are then calcinedin air and the metals are converted into their oxide forms, which do notpresent hydrogenation activity. In order to be active for hydrogenationthese oxides are converted into metal sulfides, for example metalsulfides of Mo, Ni, or W, or the metal oxides can be reduced to theirelemental metal form, for example elemental forms of Mo, Pt, Re, Pd, orRh. In one or more embodiments, the composite zeolite catalyst isimpregnated with rhenium in the form of ammonium perrhenate (NH₄ReO₄) asa metal precursor through an incipient wetness procedure. In one or moreembodiments, the composite zeolite catalyst is impregnated withmolybdenum in the form of ammonium molybdate tetrahydrate((NH₄)₆Mo₇O₂₄.4H₂₀) as a metal precursor through an incipient wetnessprocedure.

In various embodiments, the impregnated metal component may be presentin only the MOR-L, only the ZSM-5, or both. For example, the impregnatedmetal component may be in the MOR-L or ZSM-5 individually from 0.01 to20.0 wt. %, or from 2 to 5 wt. %, or from 0.1 to 1.5 wt. %, or from 0.25to 0.5 wt. %, or approximately 0.3 wt. % of the MOR-L or ZSM-5.

In one embodiment, the molar ratio of silicon to aluminum (Si/Al) in theMOR-L is from 4:1 to 10:1. In further embodiments, the molar ratio ofsilicon to aluminum in the MOR-L is from 5:1 to 8:1 or from 6:1 to 7:1.

The composite zeolite catalyst and the MOR-L and ZSM-5 individualcomponents comprise porosity. A micropore volume and a mesopore volumerepresent the specific volumes corresponding to the microporousstructure and to the mesoporous structure, respectively. The mesoporesare mainly due to intercrystalline voids formed, because of the verysmall size of the zeolite crystals. The pore size ranges for mesoporesand micropores are in conformity with conventionally understood sizeranges for such pore classifications with micropores representing poresunder 2 nanometers (nm) in diameter and mesopores representing pores of2 to 50 nm in diameter. A total pore volume would additionally includeany macropores if present.

From a property standpoint, in one or more embodiments, the MOR-L mayhave a micropore volume (V_(micro)) of at least 0.15 cubic centimetersper gram (cm³/g), or a micropore volume of at least 0.16 cm³/g, amicropore volume of 0.15 to 0.25 cm³/g, or a micropore volume of 0.16 to0.2 cm³/g. The micropore volume may be calculated by the t-plot methodof determining micropore volume known to one having skill in the art.Similarly, in one or more embodiments, the MOR-L may have a mesoporevolume (V_(meso)) of at least 0.15 cubic centimeters per gram (cm³/g), amesopore volume of at least 0.2 cm³/g, a mesopore volume of 0.15 to 0.3cm³/g, or a mesopore volume of 0.2 to 0.3 cm³/g. The mesopore volume maybe calculated according to the Barrett-Joiner-Halenda (BJH) method ofdetermining mesopore volume known to one having skill in the art.Details regarding the t-plot method and the BJH method of calculatingmicropore volume and mesopore volume respectively are provided inGalarneau et al., “Validity of the t-plot Method to Assess Microporosityin Hierarchical Micro/Mesoporous Materials”, Langmuir 2014, 30,13266-13274, for example. It is noted that the MOR-L has a higherV_(meso) than commercial MOR (CBV21A) as the layered morphology of MOR-Lresults in a larger ratio of external to internal surface area.

Regarding the ZSM-5 porosity, the ZSM-5 may have a micropore volume(V_(micro)) of at least 0.05 cubic centimeters per gram (cm³/g), or amicropore volume of at least 0.10 cm³/g, a micropore volume of 0.05 to0.25 cm³/g, or a micropore volume of 0.10 to 0.20 cm³/g in accordancewith the t-plot method of determining micropore volume. Similarly, inone or more embodiments, the ZSM-5 may have a mesopore volume (V_(meso))of at least 0.01 cubic centimeters per gram (cm³/g), or a mesoporevolume of at least 0.03 cm³/g, a mesopore volume of 0.01 to 0.1 cm³/g, amesopore volume of 0.03 to 0.08 cm³/g calculated according to theBarrett-Joiner-Halenda (BJH) method of determining mesopore volume.

The surface area of the pores of the composite zeolite catalyst and theMOR-L and ZSM-5 individually affect the TMB and MEB conversion of theheavy reformate. An increased surface area provides increasedinteraction between the individual catalyst components and theconstituents of the heavy reformate feed allowing for increasedconversion activity.

In one or more embodiments, the MOR-L may have a surface area defined bya Brunauer-Emmett-Teller (BET) analysis (S_(BET)) of at least 300 squaremeters per gram (m²/g), a S_(BET) surface area of at least 425 m²/g, ora S_(BET) surface area of at least 450 m²/g. Further, the MOR-L may havea micropore surface area (S_(micro)) of 300 m²/g to 400 m²/g. Themicropore surface area may be calculated directly from the microporevolume. Additionally, the zeolite composite catalyst may have anexternal surface area (S_(Ext)) of at least 100 m²/g, 100 to 250 m²/g,100 to 200 m²/g, or 100 to 175 m²/g. It is noted that the externalsurface area is obtained as the difference between the BET surface areaand the micropore surface area. It is noted that the MOR-L has a higherS_(Ext) than commercial MOR (CBV21A) as the layered morphology of MOR-Lresults in a larger ratio of external to internal surface area.

In one or more embodiments, the ZSM-5 may have a surface area defined bya Brunauer-Emmett-Teller (BET) analysis (S_(BET)) of at least 300 squaremeters per gram (m²/g), a S_(BET) surface area of at least 325 m²/g, ora S_(BET) surface area of at least 350 m²/g. Further, the ZSM-5 may havea micropore surface area (S_(micro)) of 275 m²/g to 400 m²/g. In one ormore embodiments, the ZSM-5 zeolite catalyst is a commercially availableZSM-5. For example, the ZSM-5 may be CBV3024E from Zeolyst International(Conshohocken, Pa., USA).

MOR-L is not a commercially available zeolite catalyst and thereforemust be synthesized for utilization in the composite zeolite catalyst.It will be appreciated that various synthesis procedures may be utilizedto prepare the MOR-L for utilization in the composite zeolite catalyst.In one embodiment, the synthesis of the MOR-L comprises combining asilicon source and an organic structure directing agent, and an aluminumprecursor in a reagent container to form a catalyst gel. The catalystgel is then heated to form the composite zeolite catalyst particles. Oneexample synthesis procedure is detailed in the Examples section of thisdisclosure.

EXAMPLES

The described embodiments will be further clarified by the followingexamples and comparative examples.

The following synthesis procedure for MOR-L serves as an example anddiffering synthesis procedures may equally be utilized to prepare theMOR-L for utilization in the composite zeolite catalyst.

For demonstration purposes, composite zeolite catalysts and theconstituents of the composite zeolite catalysts were prepared inaccordance with one or more embodiments of this disclosure. Compositezeolite catalyst particles were synthesized with rhenium incorporatedinto the catalyst particles. Rhenium was incorporated into the samplesat 0.3 wt. % by means of the incipient wetness procedure using ammoniumperrhenate (NH₄ReO₄) as a metal precursor. The rhenium was incorporatedinto the MOR-L and ZSM-5 individually and the generated zeolites werethen physically mixed in a 60:40 MOR-L:ZSM-5 weight ratio to generateExample 1.

To synthesize MOR-L, 0.177 g of NaAlO₂ (Al₂O₃ 57.6 wt. %, Na₂O 37.9 wt.% and H₂O 4.5 wt. %) was added to a 3.135 g of a solution of NaOH (10wt. %). Additionally, 1.087 g of C₂₂₋₆₋₆Br₂ (molar weight=724.48 g/mol)was added as an organic structure-directing agent. Finally, 3.005 g ofLudox AS-40 (Sigma-Aldrich) was added as a silicon source to form thecatalyst gel. The resulting molar composition of the catalyst gel was0.25 Na₂O : 1 SiO₂ : 0.05 Al₂O₃ : 0.075 C₂₂₋₆₋₆Br₂ : 40 H₂O inconformity with Table 1. The gel with the desired composition wasintroduced into an autoclave lined with polytetrafluoroethylene at 150°C. under stirring at 60 rpm and autogenous pressure for 5 days. In afinal step, the resultant powder from the autoclave was filtered andwashed with hot water (50° C.), and dried in an oven at 100° C.overnight. The acid zeolite was obtained by ion exchange with NH₄Cl(2.5M solution at 80° C. for 1h) and calcined with air flow at 500° C.for 8 hours.

TABLE 1 Gel Composition Sample Composition MOR-L 0.25 Na₂O: 1 SiO₂: 0.05Al₂O₃: 0.075 C₂₂₋₆₋₆Br₂: (Si/Al = 6.5) 40 H₂O

For demonstration purposes, a composite zeolite catalyst was prepared inaccordance with one or more embodiments of this disclosure. Thecomposite zeolite catalyst was formed as a physical mixture of rheniumcontaining MOR-L and rhenium containing ZSM-5. Pure MOR-L and pure ZSM-5zeolites were impregnated with rhenium. Rhenium was incorporated intoeach sample at 0.3 wt. % by means of the incipient wetness procedureusing ammonium perrhenate (NH₄ReO₄) as a metal precursor. After rheniumloading, the samples were stored in a desiccator for at least 5 hoursand then dried at 100° C. overnight. The rhenium loaded MOR-L and ZSM-5were mixed in a 60:40 weight ratio of MOR-L:ZSM-5. The ZSM-5 was thecommercially available CBV3024E (Zeolyst International). The physicalmixture was calcined in a fixed bed reactor with the temperatureincreased up to 500° C. in a flow of nitrogen gas (N₂) at 100 milliliterper minute (ml/min) and then maintained at 500° C. for 3 hours under airflow at 100 ml/min. The sample was then cooled to room temperature orreduction temperature under a nitrogen flow at 100 ml/min. The preparedcomposite zeolite catalyst with a 60:40 weight ratio ofRe/MOR-L:Re/ZSM-5 is designated as Example 1. Pure generated MOR-L wasdesignated as Example 2 (comparative) and the rhenium impregnated MOR-Lwas designated as Example 3 (comparative).

Comparative zeolite catalyst samples were also prepared for comparisonwith the composite zeolite catalyst particles. ATA-21 (ComparativeExample 4) represents a commercial catalyst based on a physical mixtureof Mordenite and ZSM-5, CBV21A (Zeolyst International) representscommercially available Mordenite (Comparative Example 5), and CBV3024E(Zeoyst International) represents commercially available ZSM-5(Comparative Example 6). Samples of the commercially available pure MORand ZSM-5 were also prepared with rhenium incorporated into eachcatalyst. As with the composite zeolite catalyst, rhenium wasincorporated into each sample. The CBV21A (commercially available MOR)with incorporated rhenium was designated as Comparative Example 7, andthe CBV3024E (commercially available ZSM-5) with incorporated rheniumwas designated as Comparative Example 8. Rhenium was incorporated intoall of the samples at 0.3 wt. % by means of the incipient wetnessprocedure using ammonium perrhenate (NH₄ReO₄) as a metal precursor.Rhenium containing CBV21A and rhenium containing CBV3024E were alsomixed in a 60:40 weight ratio MOR:ZSM-5, and designated as ComparativeExample 9.

A listing of the composition of each Example is provided in Table 2.

TABLE 2 Composition of each Example EXAMPLE COMPOSITION Example 1 60 wt.% MOR-L with 0.3 wt. % rhenium and 40 wt. % ZSM-5 with 0.3 wt. % rheniumComparative Example 2 MOR-L Comparative Example 3 MOR-L with 0.3 wt. %rhenium Comparative Example 4 ATA-21 Comparative Example 5 CBV21A(Commercial Mordenite, MOR) Comparative Example 6 CBV3024E (CommerciallyZSM-5) Comparative Example 7 CBV21A with 0.3 wt. % rhenium ComparativeExample 8 CBV3024E with 0.3 wt. % rhenium Comparative Example 9 60 wt. %CBV21A with 0.3 wt. % rhenium and 40 wt. % ZSM-5 with 0.3 wt. % rhenium

The physico-chemical properties of each of the samples were quantified.Specifically, the silicon to aluminum ratio as well as the final wt. %of Re in each sample was determined for each sample type. Additionally,the micropore volume and the mesopore volume were calculated accordingto the t-plot method and the BJH correlation method respectively.Further, the micropore surface area was calculated from the microporevolume, the total specific surface area was calculated in accordancewith the Brunauer-Emmett-Teller method widely used for evaluating thesurface area of porous and finely-divided materials, and the externalsurface area was calculated based on the difference between the totalspecific surface area and the micropore surface area. Thesephysio-chemical properties are delineated in Table 3.

TABLE 3 Chemical composition and textural properties of samples ReS_(BET) S_(micro) S_(Ext) V_(micro) V_(meso) Sample Si/Al (wt. %) (m²/g)(m²/g) (m²/g) (cm³/g) (cm³/g) Comp. 10.1 — 451 425 26 0.204 0.029Example 5 (MOR) Comp. 8.9 0.3 429 408 21 0.200 0.027 Example 7 (RheniumMOR) Comp. 6.5 — 499 331 168 0.162 0.238 Example 2 (MOR-L) Comp. 6.1 0.3470 357 113 0.174 0.152 Example 3 (Rhenium MOR-L) Comp. 13.0 — 372 33240 0.162 0.055 Example 6 (ZSM-5) Comp. 13.4 0.3 365 327 39 0.159 0.054Example 8 (Rhenium ZSM-5)

Table 3 illustrates that the MOR-L and MOR have differing propertieswhich may have a direct effect on the catalytic behavior of a compositezeolite catalyst formed from each one respectively. It is initiallynoted that the Si/Al molar ratio of MOR-L is lower than that of the MOR.Additionally, the MOR-L comprises a greater external surface area and agreater mesopore volume. The greater S_(ext) and V_(meso) is attributedto the layered morphology of MOR-L which results in a greater ratio ofexternal to internal surface area of the formed crystals when comparedto MOR.

The acidic properties of each of the samples were also quantified.Acidity measurements were carried out by adsorption/desorption ofpyridine followed by IR spectroscopy. Self-supported wafers (10milligrams per centimeter squared (mg cm⁻²)) of calcined samples,previously activated at 400° C. and 10⁻² Pascal (Pa) overnight in aPyrex vacuum cell, were allowed to come in contact with 6.5×10² Pa ofpyridine vapor at room temperature and desorbed in vacuum at increasingtemperatures (150° C., 250° C. , and 250° C.). The spectra were recordedat room temperature. All the spectra were scaled according to the sampleweight. Brønsted and Lewis acidity of the samples compared are given inarbitrary units, according to the intensity of the bands assigned to thepyridine interacting with the Brønsted and Lewis acid sites of thezeolites (1550 and 1450 cm⁻¹, respectively). These acidic properties arelisted in Table 4.

TABLE 4 Acidic properties of samples Brønsted Acidity (u.a.) LewisAcidity (u.a.) Sample B150 B250 B350 B350/B250 L150 L250 L350 Comp.Example 5 618 487 373 0.48 51 — — (MOR) Comp. Example 7 400 363 299 0.7565 — — (Rhenium MOR) Comp. Example 2 369 278 180 0.49 125 — — (MOR-L)Comp. Example 3 312 274 192 0.62 108 — — (Rhenium MOR-L) Comp. Example 6439 395 337 0.77 51 36 32 (ZSM-5) Comp. Example 8 411 336 293 0.71 94 6861 (Rhenium ZSM-5)

Table 4 illustrates that MOR-L (Comparative Examples 2 and 3) presents alower Brønsted acid density and higher number of Lewis acid sites incomparison with MOR (Comparative Examples 5 and 7). The difference inBrønsted acid site density and number of Lewis acid sites may beattributed to the presence of extraframework Aluminum (EFAL) with partof the EFAL generating more Lewis acid sites while neutralizing bridginghydroxyl groups, thereby decreasing the Brønsted acid density. Withreference to FIG. 4, enclosing the ²⁷Al-NMR spectra, the EFAL inComparative Example 2 (MOR-L) is indicated by the extra band appearingat a chemical shift close to −3 parts per million (ppm). It is notedthat no band is indicated for Comparative Example 5 (MOR).

With reference to FIG. 5, enclosing the Fourier transformed infraredspectra, the bands from Comparative Example 2 (MOR-L) and ComparativeExample 5 (MOR) may be compared. The spectra for both before pyridineadsorption (represented as a solid line) and after pyridine adsorptionat 150° C. (represented as a dotted line) are presented. It is notedthat Comparative Example 2 (MOR-L) presents a more intense band at 3745cm⁻¹ than Example 5 (MOR), the band corresponding to external SiOH whichis in agreement with the higher external surface area. Further,comparing the band at 3600 cm⁻¹, which corresponds to the acidhydroxyls, it may be concluded that most of the acid sites ofComparative Example 2 (MOR-L) sample are able to interact with the basicprobe molecule, while conversely only a portion of the Brønsted acidsites for Comparative Example 5 (MOR) are accessible to pyridine.Finally, comparing the band at 3680 cm⁻¹, which corresponds to externalextraframework Al species, it may be concluded that Comparative Example2 (MOR-L) comprises the EFAL, whereas Comparative Example 5 (MOR) doesnot.

As stated previously, the present composite zeolite catalyst represent adealkylation and transalkylation catalyst suitable for converting C₉₊alkyl aromatic hydrocarbons to a product stream comprising benzene,toluene, and xylenes, particularly to commercially valuable xylenes. Thefeed stream to the conversion process generally comprises alkylaromatichydrocarbons in the carbon number range C₉ to C₁₁₊ that may include, forexample, such hydrocarbons as propylbenzenes, methylethylbenzenes,tetramethylbenzenes, ethyldimethylbenzenes, diethylbenzenes,methylpropylbenzenes, and mixtures thereof. For purposes of testing andquantifying the examples and comparative examples a simulated heavyreformate feed was generated. The simulated heavy reformate feedcomprises 30 wt. % para-methylethylbenzene (p-MEB) and 70 wt. %1,2,4-trimethylbenzene (1,2,4-TMB).

Catalytic test for conversion of the simulated heavy reformate feed wereperformed in a reaction system comprising sixteen (16) continuousfixed-bed parallel microreactors. Each reactor was capable of being fedindependently with the desired flow of the simulated reformate feed andH₂ making it possible to operate in a wide range of contact times andhydrogen/hydrocarbon molar ratios. The simultaneous catalyticexperiments were carried out under the following conditions: 20 bartotal pressure, a hydrogen/hydrocarbon molar ratio of 8.5, a reactiontime of 16 hours per temperature, and a weight hourly space velocity(WHSV) of 10 inverse hours (h⁻¹). After the testing at each temperaturethe zeolitic catalysts were kept at that temperature and under H₂atmosphere for an additional 10 hours. Each zeolitic catalyst sample wasprepared to a particle size of 0.2 to 0.4 millimeters (mm). The testedzeolitic samples included Example 1 (60:40 weight ratio MOR-L:ZSM-5 with0.3 wt. % rhenium), Comparative Example 4 (ATA-21), Comparative Example3 (MOR-L with 0.3 wt. % rhenium), Comparative Example 7 (MOR with 0.3wt. % rhenium) and Comparative Example 9 (60 wt. % CBV21A with 0.3 wt. %rhenium and 40 wt. % ZSM-5 with 0.3 wt. % rhenium). Comparative Example4 (ATA-21) is a commercially available heavy reformate conversioncatalyst based on a physical mixture of Mordenite and ZSM-5 zeolites andserves as a comparative example for the composite zeolite catalystscomprising MOR-L and ZSM-5. Similarly, Comparative Example 7 (MOR with0.3 wt. % rhenium) is a commercially available Mordenite zeolite(CBV21A) and serves as a comparative example for the composite zeolitecatalysts comprising MOR-L with 0.3 wt. % rhenium (Comparative Example3), which further serves as a comparative example for the compositezeolite catalysts comprising rhenium containing MOR-L and ZSM-5 and thesynergistic effect of both components. Finally, Comparative Example 9 isa physical mixture of 60 wt % rhenium loaded commercial CBV21A and 40 wt% rhenium loaded CBV3024E, and serves as a comparative example for thecomposite zeolite catalysts comprising rhenium containing MOR-L andZSM-5.

Each fixed-bed microreactor reactor was prepared with 125 mg of thezeolitic catalyst sample and diluted with silicon carbide (SiC) to atotal bed volume of 2.0 ml for testing. The experiments were performedon the same zeolite weight basis so in Comparative Example 4 (ATA-21)the amount of catalyst added was adjusted according to its zeolitecontent in order to have 125 mg of zeolite excluding the matrix. Fourconsecutive reactions phases were completed at temperatures of 350° C.,375° C., 400° C., and a return to 350° C.

The reaction products from each of the fixed-bed microreactors wereanalyzed by on-line gas chromatography using two independent channels(Bruker 450 Gas Chromatograph). Argon (Ar) as an internal standard, H₂,methane, and ethane were analyzed in a first channel equipped with athermal conductivity detector (TCD) and three columns. The three columnswere a Hayesep N pre-column (0.5 m length) (Hayes Separations, Inc.), aHayesep Q (1.5 m length) (Hayes Separations, Inc.), and a 13X molecularsieve (1.2 m length). In a second channel the C₁-C₄ hydrocarbons werefirst separated from the aromatics in a CP-Wax capillary column (5.0 mlength and 0.32 mm inner diameter) (Cole-Parmer). Subsequently, theC₁-C₄ gases were separated in a column with CP-PoraBOND Q (25 m lengthand 0.32 mm inner diameter) (Cole-Parmer) and detected in a flameionization detector (FID). Separation of the aromatics was completed ina second CP-Wax (1.0 m length and 0.32 mm inner diameter) connected to asecond FID.

With reference to FIGS. 6, 7 and 8, the MEB conversion (dealkylation),TMB conversion (transalkylation), and overall conversion (MEB+TMB) areillustrated for each of Example 1, Comparative Example 3, ComparativeExample 4, comparative Example 7, and Comparative Example 9 versus timeon stream (TOS). It is noted that Example 1 did not exhibit deactivationduring the testing procedure. This phenomenon is indicated by theconversion percentage for the initial 350° C. stage at the beginning ofeach test and the final 350° C. stage at the conclusion of each testbeing similar.

The lack of deactivation observed for the composite zeolite catalyst isbelieved to be due to its higher catalytic efficiency, which reduces theformation of heavy alkylaromatics. The proximity of the two zeolitephases (ZSM-5 and MOR-L) because of the physical mixture of the twozeolite phases in a single catalyst and reactor allows the TMB presentin the feed to preferentially react on the MOR-L crystals with thetoluene previously formed by dealkylation of MEB on the ZSM-5 crystals.In fact, the overall conversion obtained with Example 1 is higher thanthe one obtained with Comparative Example 3, based on pure MOR-L with noZSM-5, due to a lower in-situ production of toluene. Additionally, thelayered morphology of the MOR-L crystals creates short diffusionpathways which allow the products to diffuse out of the zeolite crystalsbefore undergoing reactions into heavier aromatics, coke precursors, orboth. This reduced formation of A₁₀₊ and coke precursors leads toimproved catalyst life.

With reference to FIGS. 9, 10, 11, 12, 13, 14 and 15, the xylenes yield,A₁₀ yield, A₁₀₊ yield, light hydrocarbon yield, toluene yield,ethylbenzene yield, and benzene yield are respectively illustrated foreach of the 5 sample types versus TOS. It is noted that Example 1 (60:40weight ratio MOR-L:ZSM-5 with 0.3 wt. % rhenium) favors the xylenesproduction as compared to Comparative Example 3 (MOR-L with 0.3 wt. %rhenium), and Comparative Example 9 (60 wt. % CBV21A with 0.3 wt. %rhenium +40 wt. % CBV3024E with 0.3 wt. % rhenium). The higherselectivity to xylenes is believed a consequence of the lower productionof undesirable A₁₀₊ aromatics. As indicated in FIG. 11, Example 1 (60:40weight ratio MOR-L:ZSM-5 with 0.3 wt. % rhenium) demonstrated the lowestyield of A₁₀₊ aromatics.

The results generated from testing the samples with the simulated heavyreformate provided information regarding the relative activity of thedifferent catalyst compositions and their stability towards deactivationwith an extended TOS. The catalysts were also tested under conditionscloser to industrial conditions which would be observed for conversionof heavy reformate to xylenes. To more accurately reflect industrialconditions a supply of actual industrial heavy reformate with knowncomposition was utilized. Table 5 delineates the composition of theindustrial heavy reformate used for testing and Table 6 provides therelative ratios of various components.

TABLE 5 Industrial Heavy Reformate Composition Component HydrocarbonType Hydrocarbon Sub-Type Mass % A₈ Total 3.94 Ethylbenzene 0.03p-xylene 0.15 m-xylene 0.38 o-xylene 3.38 A₉ Total 82.75Isopropylbenzene Total 0.43 n-propylbenzene Total 2.07Methylethylbenzene Total 19.62 (MEB) m- and p-MEB 15.33 o-MEB 4.29Trimethylbenzene Total 60.63 (TMB) 1,3,5-TMB 11.69 1,2,4-TMB 40.811,2,3-TMB 8.13 A₁₀₊ Total 13.33

TABLE 6 Industrial Heavy Reformate Composition Ratio A₈Ethylbenzene:Total A₈ 0.0076 p-xylene:Total A₈ 0.038 m-xylene:Total A₈0.096 o-xylene:Total A₈ 0.858 A₉ Isopropylbenzene:Total A₉ 0.0052n-propylbenzene:Total A₉ 0.025 Total Methylethylbenzene (MEB):Total A₉0.237 m- and p-MEB:Total A₉ 0.185 o-MEB:Total A₉ 0.052 m- andp-MEB:Total MEB 0.781 o-MEB:Total MEB 0.219 Total Trimethylbenzene(TMB):Total A₉ 0.733 1,3,5-TMB:Total A₉ 0.141 1,2,4-TMB:Total A₉ 0.4931,2,3-TMB:Total A₉ 0.098 1,3,5-TMB:Total TMB 0.193 1,2,4-TMB:Total TMB0.673 1,2,3-TMB:Total TMB 0.124 Total A₉:Total A₁₀₊ 6.21

Catalytic tests for conversion of the industrial heavy reformate feedwere performed in a fixed-bed stainless-steel tubular reactor. Thereactor had a 10.5 mm internal diameter and a 20 centimeter (cm) length.The catalytic experiments in the fixed-bed tubular reactor were carriedout under the following conditions: 20 bar total pressure, ahydrogen/hydrocarbon molar ratio of 4:1, a reaction time of 3 hours ateach reaction temperature, and a weight hourly space velocity (WHSV) of10 h⁻¹. The reactor was charged with 0.75 grams (g) of catalyst with aparticle size of 0.2 to 0.4 mm for each test. The tested zeoliticsamples included Example 1 (60:40 weight ratio MOR-L:ZSM-5 with 0.3 wt.% rhenium), Comparative Example 4 (ATA-21), Comparative Example 3 (MOR-Lwith 0.3 wt. % rhenium), Comparative Example 7 (MOR with 0.3 wt. %rhenium), and Comparative Example 9 (60 wt. % CBV21A with 0.3 wt. %rhenium and 40 wt. % ZSM-5 with 0.3 wt. % rhenium). The catalyst wasdiluted with SiC to bring the total volume up to a total bed volume of5.0 ml. For Comparative Example 4 (ATA-21), the amount of catalyst addedwas adjusted according to its zeolite content in order to have 0.75 g ofzeolite (the matrix was excluded). Gaseous compounds (H₂, N₂) were fedinto the system by mass flow meters via a vaporizer. Nitrogen was alsofed into the system as an internal reference. The industrial heavyreformate was fed by means of a high performance liquid chromatography(HPLC) pump to the vaporizer. The vaporizer was operated at 300° C. andprovided a steady and non-pulsing flow of reactants to the reactor.Prior to commencing the catalytic test, the catalyst was reduced in situat 450° C. for 1 h under H₂ flow (50 ml/min) at atmospheric pressure.For the catalytic testing, four consecutive reactions phases werecompleted at temperatures of 350° C. (7 h reaction), 375° C. (5 hreaction), 400° C. (5 h reaction), and a return to 350° C. (5 hreaction).

During reaction, the effluent stream was analyzed on-line at intervalsof 32 minutes (min) in a Scion 456 Gas Chromatograph equipped with twodetection channels. Nitrogen (N₂) as an internal standard, H₂, methane,and ethane were analyzed in a first channel equipped with a TCD andthree columns. The three columns were a Hayesep N pre-column (0.6 mlength) (Hayes Separations, Inc.), a Hayesep Q (1.6 m length) (HayesSeparations, Inc.), and a 13X molecular sieve (1.2 m length). In asecond channel the C₁-C₄ hydrocarbons were first separated from thearomatics in a CP-Wax capillary column (5.0 m length and 0.32 mm innerdiameter) (Cole-Parmer). Subsequently, the C₁-C₄ gases were separated ina column with CP-PoraBOND Q (25 m length and 0.32 mm inner diameter)(Cole-Parmer) and detected in a flame ionization detector (FID).Separation of the aromatics was completed in a second CP-Wax (39.5 mlength and 0.32 mm inner diameter) connected to a second FID.

With reference to FIGS. 16, 17 and 18, the TMB conversion(transalkylation), MEB conversion (dealkylation), and overall conversion(MEB+TMB) are respectively illustrated for each of Example 1,Comparative Example 3, Comparative Example 4, Comparative Example 7, andComparative Example 9. It is noted that Example 1 (60:40 weight ratioMOR-L:ZSM-5 with 0.3 wt. % rhenium) demonstrated greater overallconversion than the Comparative Examples which is attributed to thegreater TMB conversion activity. The individual TMB conversionpercentages and MEB conversion percentages are provided in Table 7.

TABLE 7 TMB, MEB, and Overall Conversion TMB MEB Overall Conver- Conver-Conver- Catalyst Temperature sion (%) sion (%) sion (%) Example 1 350°C. 43.12 79.36 52.85 (60:40 weight ratio 375° C. 51.25 91.38 62.03MOR-L:ZSM-5 with 400° C. 55.81 96.32 66.69 0.3 wt. % rhenium)Comparative Example 3 350° C. 35.26 49.43 39.00 (MOR-L with 0.3 wt. %375° C. 36.54 59.55 42.62 rhenium) 400° C. 41.28 75.06 50.21 350° C.15.15 29.00 18.81 (Return) Comparative Example 4 350° C. 22.22 70.5334.18 (ATA-21) 375° C. 37.64 94.12 51.62 400° C. 34.62 98.72 50.48 350°C. 27.44 74.76 39.15 (Return) Comparative Example 7 350° C. 23.08 40.8127.76 (MOR with 0.3 wt. % 375° C. 31.92 61.07 39.62 rhenium) 400° C.42.55 77.44 51.77 350° C. 15.89 35.84 21.16 (Return) Comparative Example9 350° C. 22.51 73.84 36.08 (60:40 weight ratio 375° C. 38.86 88.4651.96 MOR-:ZSM-5 with 0.3 400° C. 40.50 97.49 55.56 wt. % rhenium) 350°C. 28.19 66.55 38.32 (Return)

With reference to FIGS. 19, 20, 21, 22, 23, 24, and 25, the xylenesyield, A₁₀ yield, A₁₀₊ yield light hydrocarbon yield, toluene yield,ethylbenzene yield, and benzene yield are respectively illustrated foreach of Example 1, Comparative Example 3, Comparative Example 4,Comparative Example 7, and Comparative Example 9. It is noted, withreference to FIG. 19, that Example 1 significantly favors the xylenesproduction as compared to Comparative Examples 3, 4, 7, and 9 for allreaction temperatures. As xylenes are the desirable product, theincreased yield of xylenes with the composite zeolite catalystcomprising MOR-L and ZSM-5 is a positive result. The higher selectivityto xylenes is believed a consequence of the lower production ofundesirable A₁₀₊ aromatics. As indicated in FIG. 21, Example 1demonstrated the lowest yield of A₁₀₊ aromatics. Similarly, Example 1also demonstrates higher yields of other desirable products includingtoluene as shown in FIG. 23, benzene as shown in FIG. 24, and lighthydrocarbons as show in FIG. 22. The numerical values of the yield as awt. % for each catalyst is provided in Table 8. This improvement inxylenes and other light hydrocarbon production and concurrent reductionin A₁₀₊ fraction illustrates the benefit of the methods of the presentdisclosure where MOR-L and ZSM-5 are in proximate contact in a singlereactor during heavy reformate feed conversion. An additional advantageis that the conversion may be completed in a single reactor, therebyreducing production complexity.

TABLE 8 Product Yields Xylenes A₁₀ A₁₀₊ Light HC Toluene EthylbenzeneBenzene Yield Yield Yield Yield Yield Yield Yield Catalyst Temperature(wt. %) (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) Example 1 350°C. 20.53 2.85 4.19 11.72 2.77 1.49 18.67 (60:40 weight ratio 375° C.26.00 1.75 3.57 13.12 3.28 0.80 21.06 MOR-L:ZSM-5 400° C. 29.68 0.973.62 14.56 3.35 0.28 20.86 with 0.3 wt. % rhenium) Comp. Example 4 350°C. 15.60 3.94 11.91 2.95 1.43 1.02 10.22 (ATA-21) 375° C. 23.28 1.559.73 9.35 1.93 0.43 13.02 400° C. 24.32 2.72 12.56 9.62 1.77 0.06 12.34350° C. 15.08 3.35 11.94 6.61 1.55 0.88 10.63 (Return) Comp. Example 3350° C. 9.42 6.17 30.69 1.62 0.51 0.91 2.80 (MOR-L with 375° C. 15.505.83 23.78 3.37 0.65 1.10 4.95 0.3 wt. % rhenium) 400° C. 22.46 4.1120.95 4.78 0.75 0.86 7.13 350° C. 8.15 8.02 15.87 0.86 0.49 0.85 2.13(Return) Comp. Example 7 350° C. 12.69 8.01 15.17 1.26 0.65 1.17 4.27(MOR with 375° C. 14.02 7.38 23.22 2.68 0.48 0.85 4.13 0.3 wt. %rhenium) 400° C. 20.71 5.29 23.87 4.93 0.63 0.57 6.31 350° C. 6.74 8.9218.81 0.85 0.34 0.59 1.72 (Return) Comp. Example 9 350° C. 11.76 3.3622.43 3.43 7.43 0.72 0.94 (60:40 weight ratio 375° C. 17.77 6.91 20.975.53 9.74 0.27 1.28 MOR-L:ZSM-5 400° C. 24.87 1.59 19.02 7.46 10.76 0.091.50 with 0.3 wt. % 350° C. 9.53 5.54 24.84 3.57 6.77 0.66 0.91 rhenium)(Return)

It should be understood that the various aspects of the method of makingBTX compounds including benzene, toluene, and xylene, and the compositezeolite catalyst utilized in the same are described and such aspects maybe utilized in conjunction with various other aspects.

In a first aspect, the disclosure provides a method of making BTXcompounds including benzene, toluene, and xylene. The method includesfeeding heavy reformate to a reactor, the reactor containing a compositezeolite catalyst comprising a mixture of layered mordenite (MOR-L). TheMOR-L comprises a layered or rod-type morphology with a layer thicknessless than 30 nm and ZSM-5, where the MOR-L, the ZSM-5, or both compriseone or more impregnated metals. The method further includes producingthe BTX compounds by simultaneously performing transalkylation anddealkylation of the heavy reformate in the reactor, where the compositezeolite catalyst is able to simultaneously catalyze both thetransalkylation and dealkylation reactions.

In a second aspect, the disclosure provides the method of the firstaspect, in which the heavy reformate comprises at least 15 wt. %methylethylbenzene (MEB) and at least 50 wt. % trimethylbenzene (TMB).

In a third aspect, the disclosure provides the method of the first orsecond aspects, in which the MOR-L comprises an external surface areagreater than 100 m²/g.

In a fourth aspect, the disclosure provides the method of any of thefirst through third aspects, in which the one or more impregnated metalsare selected from the group consisting of molybdenum, chromium,platinum, nickel, tungsten, palladium, ruthenium, gold, rhenium,rhodium, or combinations thereof and their respective oxides.

In a fifth aspect, the disclosure provides the method of any of thefirst through third aspects, in which the one or more impregnated metalscomprises rhenium.

In a sixth aspect, the disclosure provides the method of any of thefirst through fifth aspects, in which the MOR-L, the ZSM-5, or both theMOR-L and ZSM-5 comprise up to 20 wt. % of the one or more impregnatedmetals.

In a seventh aspect, the disclosure provides the method of any of thefirst through sixth aspects, in which the composite zeolite catalystcomprises a mixture of MOR-L and ZSM-5 in a 50:50 to 90:10 weight ratio.

In an eighth aspect, the disclosure provides the method of any of thefirst through sixth aspects, in which the composite zeolite catalystcomprises a mixture of MOR-L and ZSM-5 in a 55:45 to 65:35 weight ratio.

In a ninth aspect, the disclosure provides the method of any of thefirst through eighth aspects, in which the MOR-L is impregnated with0.25 to 0.5 wt.% rhenium.

In a tenth aspect, the disclosure provides the method of any of thefirst through eighth aspects, in which the ZSM-5 is impregnated with0.25 to 0.5 wt.% rhenium.

In an eleventh aspect, the disclosure provides the method of any of thefirst through tenth aspects, in which the MOR-L has a molar ratio ofsilicon to aluminum (Si/Al) from 4:1 to 8:1

In a twelfth aspect, the disclosure provides a composite zeolitecatalyst. The composite zeolite catalyst comprises a mixture of layeredmordenite (MOR-L) comprising a layered or rod-type morphology with alayer thickness less than 30 nm and ZSM-5, where the MOR-L, the ZSM-5,or both comprise one or more impregnated metals.

In a thirteenth aspect, the disclosure provides the composite zeolitecatalyst of the twelfth aspect, in which the MOR-L comprises an externalsurface area greater than 100 m²/g.

In a fourteenth aspect, the disclosure provides the composite zeolitecatalyst of the twelfth or thirteenth aspects, in which the one or moreimpregnated metals are selected from the group consisting of molybdenum,chromium, platinum, nickel, tungsten, palladium, ruthenium, gold,rhenium, rhodium, or combinations thereof and their respective oxides.

In a fifteenth aspect, the disclosure provides the composite zeolitecatalyst of the twelfth through fourteenth aspects, in which the one ormore impregnated metals comprises rhenium.

In a sixteenth aspect, the disclosure provides the composite zeolitecatalyst of the twelfth through fifteenth aspects, in which the MOR-L,the ZSM-5, or both the MOR-L and ZSM-5 comprise up to 20 wt. % of theone or more impregnated metals.

In a seventeenth aspect, the disclosure provides the composite zeolitecatalyst of the twelfth through sixteenth aspects, in which thecomposite zeolite catalyst comprises a mixture of MOR-L and ZSM-5 in a50:50 to 90:10 weight ratio.

In an eighteenth aspect, the disclosure provides the composite zeolitecatalyst of the twelfth through sixteenth aspects, in which thecomposite zeolite catalyst comprises a mixture of MOR-L and ZSM-5 in a55:45 to 65:35 weight ratio.

In a nineteenth aspect, the disclosure provides the composite zeolitecatalyst of the twelfth through eighteenth aspects, in which the MOR-Lis impregnated with 0.25 to 0.5 wt. % rhenium.

In a twentieth aspect, the disclosure provides the composite zeolitecatalyst of the twelfth through eighteenth aspects, in which the ZSM-5is impregnated with 0.25 to 0.35 wt. % rhenium.

In a twenty-first aspect, the disclosure provides the composite zeolitecatalyst of the twelfth through twentieth aspects, in which the MOR-Lhas a molar ratio of silicon to aluminum (Si/Al) from 4:1 to 10:1.

It should be apparent to those skilled in the art that variousmodifications and variations can be made to the described embodimentswithout departing from the spirit and scope of the claimed subjectmatter. Thus, it is intended that the specification cover themodifications and variations of the various described embodimentsprovided such modification and variations come within the scope of theappended claims and their equivalents.

Throughout this disclosure ranges are provided. It is envisioned thateach discrete value encompassed by the ranges are also included.Additionally, the ranges which may be formed by each discrete valueencompassed by the explicitly disclosed ranges are equally envisioned.

What is claimed is:
 1. A composite zeolite catalyst, the compositezeolite catalyst comprising a mixture of layered mordenite (MOR-L) andZSM-5, where: the MOR-L or both the MOR-L and ZSM-5 comprise one or moreimpregnated metals, the MOR-L comprises a rod morphology with a smallestdimension less than 28 nm, the MOR-L without the impregnated metalscomprises an external surface area greater than 120 m²/g, and the MOR-Lhas a molar ratio of silicon to aluminum (Si/Al) from 4:1 to 8:1.
 2. Thecomposite zeolite catalyst of claim 1, where the one or more impregnatedmetals are selected from the group consisting of molybdenum, chromium,platinum, nickel, tungsten, palladium, ruthenium, gold, rhenium,rhodium, or combinations thereof and their respective oxides.
 3. Thecomposite zeolite catalyst of claim 1, where the one or more impregnatedmetals comprises rhenium.
 4. The composite zeolite catalyst of claim 1,where the MOR-L or both the MOR-L and ZSM-5 comprise up to 20 wt. % ofthe one or more impregnated metals.
 5. The composite zeolite catalyst ofclaim 1, where the MOR-L is impregnated with 0.25 to 0.5 wt. % rhenium.6. The composite zeolite catalyst of claim 5, where the ZSM-5 isimpregnated with 0.25 to 0.5 wt. % rhenium.
 7. The composite zeolitecatalyst of claim 1, where the composite zeolite catalyst comprises amixture of MOR-L and ZSM-5 in a 50:50 to 90:10 weight ratio.
 8. Thecomposite zeolite catalyst of claim 1, where the composite zeolitecatalyst comprises a mixture of MOR-L and ZSM-5 in a 55:45 to 65:35weight ratio.
 9. The composite zeolite catalyst of claim 1, where theMOR-L has a micropore volume of 0.15 to 0.25 cm³/g.
 10. The compositezeolite catalyst of claim 1, where the MOR-L has a mesopore volume of0.15 to 0.3 cm³/g.
 11. The composite zeolite catalyst of claim 1, wherethe MOR-L comprises a rod morphology with a smallest dimension less than20 nm.
 12. The composite zeolite catalyst of claim 1, where the MOR-Lcomprises a greater external to internal surface area ratio than MOR ofthe same composition.